1. Field of the Invention
The present invention relates to an image-correspondence position detection device and a distance measuring device provided with same. The present invention further relates to an image-correspondence position detection device or apparatus provided with a distance measuring device such as, for example, a still camera, movie camera, three-dimensional measuring device and the like.
2. Description of the Related Art
Conventionally, non-TTL type passive distance measuring devices for measuring the distance to an object based on the triangulation principle have been realized by combining a pair of optical systems and a pair of image sensors. This principle measures the mutual correspondence position of images formed on a pair of sensors, and converts this position to a distance. In order to measure the correspondence position, the output of a specific plurality of pixels must be sampled from the output of each sensor, and the degree of mutual correspondence of the sampled outputs must be measured.
On the other hand, when two or more objects F and T having different distances within a distance measuring area M are included, as in the example shown in FIG. 1, the output of each sensor changes in accordance with contrast and distance of the object F and T, and the image size ratio within the measurement area M. As a result, a value mixing the object distances of objects F and T, i.e., a completely erroneous value is obtained as the distance measurement data.
There are methods for evaluating the degree of correspondence using a specific evaluation value such as minimum correlation value (Ym) or a ratio of minimum correlation value and contrast (Ym/C) so as to prevent this situation. However, the degree of correspondence can be obtained only for the entire distance measurement area.
Furthermore, even when the distance measurement data more or less accurately represent the distance of one or another among a plurality of objects, it cannot be known for which part within the distance measurement area the distance is representative.
Therefore, the mutual boundaries of objects necessitated when trying to recognize the shape of the object cannot be accurately recognized.